There is a misconception that good ‘.COM’ domain names are hard to find and so they are more expensive to buy. But once again, this statement holds no water. You can easily check out the ‘.COM’ domain names that are on sale at highly affordable prices. However, the only downside to flipping ‘.COM’ domain names is that you will have to discover them at different places like or private seller portfolios.

Wait for people to contact me: When I bought my two domains, I didn’t pay the extra $12 for Domain Privacy, learn about Domain Privacy here, so anyone can look up the owner of IHateCold(.com) and ReallyFunnyJoke(.com) in the ICANN WHOIS Database. It can tell you whoever owns any website unless that domain owner pays for domain privacy. So if someone was really interested in any of my websites, they could look me up and shoot me an email about their interest.
Determine your domain's value. Before you start taking offers or listing your domain, take stock of its value so that you can come up with a good price. There are a lot factors to take into consideration when determining the value of a domain, so if you are unsure it may be wise to contact a company that performs these assessments. Some of the major factors include:
Be careful! When searching for domains, it might be tempting to, for instance, buy (if it were available) and then try to sell it to McDonald's. The logic here would be that they own the .com and wouldn’t want anyone to own the .net and use their name, right? Also, it’s a big name so there’s gotta be a biiiiiiig payday comin’, RIGHT? Wrong, and wrong.
You can easily find domains using the best metrics available from Ahrefs, Moz, Majestic, SEMRush, Similar Web, SEMrush, Domain Scope and Social Networks. We buy only the best, the latest, and, the most comprehensive industry wide metrics so you have the maximum amount of information to make a decision. No other tool gives you access to 90+ metrics.
Namejet is a domain clearing house (at least that is my term for it).  What happens is that people let their domain names expire everyday.  Some people just don’t need their domain anymore, some people forget to renew it, some people die, I mean there can be hundreds of reasons why a domain will not be renewed.  What the domain registrars want to do is cash in on the domain that someone forgot to renew, so they offer that domain to Namejet to auction it to the general public.  Think of it like a storage unit, someone doesn’t make their payment and the storage company hires an auctioneer to come and auction the storage unit to the general public.  Namejet is doing this but for domain names.  The bid for each domain starts at $69.  What I LOVE about Namejet is the process…  they let you search through the domains that are coming up for auction 30 days in advance.  Whoever places a $69 bid on a domain will be entered into an auction when the 30 days runs out with everyone else who placed a bid.  If you are the only bidder than you get the domain for $69.  If there are 10 other bidders than there is a closed auction, meaning only you 10 guys can bid now against each other in a 3 day auction with the highest bidder taking the domain when the clock strikes zero.  I love this because let’s say there is a great domain and it flies under the radar.  If it goes to auction with only 3 or 5 or 7 bidders my chances of winning this domain at a very low price are great.  I’ve won domains for $100 which I was able to flip for $2,000.  I won a domain for $2,500 which I flipped within 4 months  for $7,500.  I won a domain for $1,000 which I’ve turned down $5,000 offers on because I think I can get $10,000 for it.  The key is to not overpay in order to leave yourself plenty of room to turn a profit when you flip the domain.
Once you decide to sell a domain name, it is important to find the best market to sell it. The best way to sell a domain name is to approach buyers secretly. If you know someone who deals with domain names, it is recommended to contact him without going through the middleman. Chances are that the seller will make more profit, as he will not have to pay the middleman.
Many non-savvy internet users may not even be aware of the existence of other extensions. That said, because there are many new extensions popping up every now and then, you can often find amazing one word and 3-letter domain names with these new extensions that are otherwise almost impossible to find unregistered in the .com world. Additionally, these new extensions are becoming more and more familiar to users every day, hence it's almost certain that their value will continue to increase as time passes and wider adoption manifests. 

If you are feeling ambitious, you can link each of your domain names to its matching “buy it now” purchase page at one of the marketplaces. Another more sophisticated option would be to “park” your domain with one of the leading domain parking companies, such as DomainSponsor or SmartName and enable their built-in “for sale” message and contact mechanisms.

Length: This is pretty self-explanatory. Generally the shorter the domain name, the more valuable it is. This difference in value decreases exponentially as the name gets longer, though. For instance, the difference in price between 3 and 4 letter domains are significant, while the price difference between a 7 and 8 letter domain would usually be much less significant.